JP5187891B2 - Machining EDM machining condition setting device - Google Patents

Description

  The present invention provides a machining restriction applied to a sculpture electric discharge machining in which a discharge is generated in a machining gap formed by a tool electrode and a workpiece, and a machining hole is formed in the workpiece by discharge energy. The present invention relates to a machining condition setting device that generates and sets a combination of initial machining conditions suitable for information relating to machining indicating the above.

  The sculpting electric discharge machine places a tool electrode and a workpiece facing each other, intermittently applies a voltage pulse to the machining gap formed by the tool electrode and the workpiece, and repeatedly generates a discharge in the machining gap. Thus, a machining hole having a desired machining shape is formed in the workpiece by the discharge energy.

  With the sculpting electric discharge machining apparatus configured in this way, before machining, information on machining indicating desired machining results such as machining surface roughness or machining constraints such as tool electrode and workpiece material is provided. It is required that a plurality of types of suitable machining conditions are determined and set in the control device. Information relating to processing indicating a restriction in processing may be referred to as processing information, required specifications, and processing specifications, but is referred to as processing requirements in the present invention. An assembly of a plurality of types of processing conditions suitable for processing requirements is sometimes referred to as a processing condition sequence or a processing condition group, but is referred to as a combination of processing conditions in the present invention.

  Machining electrical discharge machining conditions include peak current value, on time (discharge current pulse width), off time (pause time), servo reference voltage (average machining voltage), polarity, no-load voltage (power supply voltage), etc. Electrical conditions, jump speed, jump time, movement conditions such as swing amount, control conditions related to specific control to control the waveform of the discharge current pulse and voltage pulse applied to the machining gap, presence or method of machining fluid jet Includes environmental conditions such as (liquid treatment).

  Depending on the specifications of the machine and the power supply device for processing, the types of processing conditions to be set and the setting method may differ. For example, the peak current value may be set as an average machining current value. Further, for example, there is a method in which the peak current value is set by the resistance value of a variable resistor in the machining power supply circuit, or by the number of conducting a plurality of switching circuits connected in parallel to each other. In general, the machining conditions are set not with real values but with parameter values that are uniquely defined by the machine main unit and the machining power supply device. Hereinafter, the machining conditions are also referred to as parameter values.

  In any case, in the EDM machine equipped with a numerical control device, machining such as machining surface roughness, machining speed (machining time), machining shape accuracy (dimensional accuracy), electrode wear ratio (electrode wear rate) As main processing conditions for determining the supply of the discharge current pulse that has a significant influence on the results (processing characteristics), it is required to set at least the peak current value, the on time, and the off time substantially.

  In electric discharge machining, the required machining surface roughness is small and the machining shape accuracy is high, so that the machining rate for each discharge needs to be reduced, so that the machining speed becomes slower. Therefore, in order to shorten the processing time, the processing is divided into a plurality of processing steps, and rough processing is performed with large discharge energy, and then finishing is performed with the discharge energy reduced. The rough cutting process that processes the workpiece roughly into the desired hole shape is the first cut, the finishing process that processes the processed surface of the roughly formed hole, the second cut, third cut, It is called as force cut. Note that the first cut may be performed by machining such as milling and then finished by electrical discharge machining, which is electrical machining.

  The machining conditions are set for each machining step so that the discharge surface energy is reduced stepwise and the machining surface roughness is reduced so that the desired machining surface roughness finally required in the final finishing machining process can be obtained. Is set. In the machining process after the second cut, the tool electrode of the same size as the previous machining process is machined with a smaller discharge energy, or the tool electrode is consumed in the previous machining process and the size may be reduced. In order to be able to machine the side surface of the workpiece, a machining method called swing machining or offset machining is used in which the tool electrode is moved relative to the machining hole side surface direction perpendicular to the machining depth direction together with the machining depth direction. It is done. Therefore, it is necessary to provide a necessary relative movement amount (swing amount) for moving the tool electrode in the side surface direction.

  When machining with higher required machining surface roughness and machining shape accuracy, first cut is performed, then the machining surface roughness is reduced in the middle machining process, and finally the desired machining shape required. Get a shape close to. Thereafter, the crest portion of the processed surface roughness is removed by one or more finishing processing steps to reduce the unevenness, and processing is performed to obtain a desired processing surface roughness in the final finishing processing step. At this time, the relative movement amount (feed amount) and the swing amount for relatively moving the tool electrode in the machining depth direction in each machining step are described in the NC program as a movement program according to the specifications of the numerical controller, There is a method in which parameter values corresponding to machining conditions are set directly or indirectly among combinations of conditions.

  FIG. 10 schematically shows a processing mode in the processing depth direction. Moreover, the processing aspect of the side surface direction is typically shown in FIG. Note that the electrode consumption is shown neglected. As shown in FIG. 10, when machining a machining hole having a machining depth D, in the first cut, which is a rough machining process for roughly machining the machining hole, the bottom surface is offset by a bottom offset H1. The tool electrode is advanced in the feed amount Z1 and the machining depth direction (bottom direction) from the machining start position given at a position separated from the upper surface reference (electrode reference position) by the discharge gap or more so that the tool electrode exists. During this time, the machining gap is maintained at a predetermined distance by a so-called servo operation.

  Accordingly, the bottom surface offset H1 in the first cut is the final value obtained by adding the bottom surface safety allowance K1 considering the variation of the processed surface roughness R1 to the bottom surface discharge gap (overcut, clearance) G1 and the processed surface roughness R1 in the first cut. This is a value obtained by subtracting the desired processed surface roughness R3, which is the finished surface roughness. Since the processing reference position is the upper surface reference, it may be considered that the feed amount Z1 is advanced from the upper surface reference.

  Regarding the side surface direction, in the first cut, similarly to the machining depth direction, the side surface offset H1 is a desired finish surface roughness from a value obtained by adding the side surface discharge gap G1, the machining surface roughness R1, and the side surface safety allowance K1. This is a value obtained by subtracting the processed surface roughness R3. Since the discharge gap exists, the tool electrode must be at a position offset with respect to the diameter of the machining hole, which is the final machining shape, so that the tool electrode is made small with respect to the size of the machining hole. As shown in FIG. 11, the tool electrode is made smaller by an electrode reduction amount (one side) L than the side surface of the machining hole. When the rocking process is not performed in the first cut, the side surface offset H1 in the first cut corresponds to the electrode reduction amount L.

  In the intermediate machining process after the second cut, the safety allowance K1 left by the first cut is removed while reducing the roughness of the machined surface. Therefore, the bottom surface offset H2 is a value obtained by subtracting a desired processing surface roughness R3 from a value obtained by adding a slight bottom surface safety allowance (not shown) to the discharge gap G2 and processing surface roughness R2 in the processing process. Further, in the side surface machining, when the rocking process is performed, the tool electrode is fed in the side surface direction by the rocking amount X2 so that the tool electrode is at a position separated by the side surface offset H2. Therefore, the side surface offset H2 is a value obtained by subtracting a desired processing surface roughness R3 from a value obtained by adding a side surface safety gap (not shown) to the side surface discharge gap G2 and processing surface roughness R2 in the processing step.

  In the finishing process in which most of the safety margin K1 of the first cut is removed and the crest of the processed surface roughness is removed to remove the irregularities, the discharge energy is sufficiently reduced. In the final finishing process, the bottom surface offset H3 is the same as the value of the bottom surface discharge gap G3, and the side surface offset H3 is the same as the value of the side surface discharge gap G3. It is processed with the discharge energy that provides the roughness R3. As shown in FIG. 10, the feed amount in the machining depth direction is based on the offset position of the preceding machining process. Further, as shown in FIG. 11, the swing amount in the side surface direction is based on the position of the side surface of the tool electrode located at the center of the machining hole.

  For this reason, in the sculpture electric discharge machining, a machining plan is devised so that a combination of machining conditions suitable for each machining process is set so that a desired machining result that is finally required can be obtained. There is a need. However, in sculpture electric discharge machining, since the tool and workpiece are electrically processed without contact, multiple types of machining conditions are closely related to each other and have a significant effect on the machining result. . In addition, there are types of machining conditions that cannot express the relationship to machining requirements with only physical formulas. Therefore, a slight difference in the combination of processing conditions may cause a large difference in the processing result, and the number of combinations of processing conditions recorded as processing data corresponding to the processing result and the processing request becomes enormous.

  Therefore, it is difficult for an operator to predict machining results in a combination of machining conditions, and the relationship between typical machining condition combinations provided by manufacturers of die-sinking electrical discharge machining equipment and machining requirements including machining results is shown. In many cases, satisfactory machining results cannot be obtained even if machining is performed with a combination of machining conditions selected and set from machining data to be set. For this reason, the machining condition setting operation is very difficult for the operator, and abundant knowledge and experience are required.

  Until now, a method for setting a number of optimum combinations of machining conditions has been considered so that a desired machining result can be obtained by facilitating an operation of generating and setting a combination of machining conditions. The basic idea of such a processing condition setting method is to record a combination of processing conditions with which a preferable processing result is obtained in a data book with a processing condition number (code) corresponding to the processing request, A combination of processing conditions suitable for the processing requirements is found, and an optimal combination of processing conditions is set based on the combination of the processing conditions.

  A widely known machining condition setting device is a desired machining result and machining request inputted from machining data of a combination of a number of machining conditions stored in advance in a storage device corresponding to the machining result or machining request. This is a configuration in which a combination of machining conditions corresponding to the parameter values is searched, extracted, and set. When there is no combination of machining conditions that match the desired machining result and machining request in the accumulated machining data, a combination of a plurality of machining conditions close to the desired machining result and machining request is extracted as a candidate. . The operator selects an optimum combination of machining conditions with a short machining time expected from a combination of candidate machining conditions. Therefore, since it is possible to select and set a combination of machining conditions that satisfy a machining request including a desired machining result by simply inputting machining request data, the machining condition setting operation is facilitated (Patent Document 1). reference).

  When there is no combination of machining conditions that matches the machining requirements and machining is performed with a combination of machining conditions that are close to the machining requirements including the desired machining results, the desired machining results are often not obtained. In view of this, a machining condition setting device is conceivable in which parameter values of specific types of machining conditions in a combination of machining conditions extracted according to an inputted machining request are changed and optimized. According to such a processing condition setting device, even if there is no processing condition combination that matches the processing request in the processing data, it is relatively easy to obtain a combination of processing conditions suitable for the processing request from a combination of processing conditions close to the processing request. Therefore, working efficiency is improved (see Patent Document 2).

  As a method of optimizing the combination of machining conditions by changing and adjusting the parameter values of specific types of machining conditions, the processing request data including the desired machining results entered from the machining condition combination data in the database There is a machining condition generation method for extracting a combination of a plurality of machining conditions close to each other and generating a combination of machining conditions in the middle of the combination of the plurality of machining conditions. According to such a machining condition generation method, a combination of machining conditions close to the machining requirements can be obtained more easily even if the database does not have machining condition combination data that matches the machining requirements. It is possible to reduce the number of processing data of combinations of processing conditions prepared in line (see Patent Document 3).

  In addition, a specific type of machining condition is determined from representative data of a specific type of machining condition corresponding to a machining request including a desired machining result as basic data, and other types of machining conditions are sequentially set according to the determined machining condition. A processing condition setting device that determines and generates a combination of processing conditions is considered. Specifically, from basic data consisting of machining current data corresponding to multiple types of machining requirements, such as machining area for each tool electrode and workpiece, machining depth, minimum side surface reduction amount, and machining surface roughness A plurality of machining currents close to the input machining requirements are extracted and learned, intermediate data of a plurality of data is obtained to determine a machining current that is a specific type of machining condition, and a predetermined calculation formula is used. On-time (discharge current pulse width) and off-time (rest time) are sequentially determined to generate a combination of machining conditions. Therefore, since the combination of the machining conditions can be determined simply by having basic data recording a specific type of machining conditions, a database in which a huge number of combinations of machining conditions are recorded is unnecessary (see Patent Document 4).

  In a machining condition setting device that generates a combination of machining conditions by sequentially determining multiple types of machining conditions, a theoretical correlation between a desired machining result and a specific type of machining condition is shown first. After determining a specific type of machining condition for the desired machining result that is input based on the data, other types of machining conditions are sequentially set based on data that shows a theoretical correlation between multiple types of similar parameters. There is a machining condition setting device that determines and generates a combination of machining conditions. Since this machining condition setting device obtains a theoretical value rather than a mere intermediate value, not only a database that records the data of the combination of machining conditions is unnecessary, but the reliability of the generated combination of machining conditions is higher, Variation in processing results can be reduced (see Patent Document 5).

JP-A-62-130131 Japanese Patent No. 2862035 Japanese Patent Laid-Open No. 5-233045 Japanese Patent No. 3231521 Japanese Patent Laid-Open No. 64-64723

  In the case of the processing condition setting device disclosed in Patent Document 1, the processing condition combination suitable for the processing request is extracted and set in relation to the entire processing condition combination and the processing result. In the combination, each type of machining condition is closely related to each other to form one combination. Therefore, even if there is a theoretical correlation between the specific type of machining condition and the machining result, There is no direct theoretical correlation between the overall combination of conditions and the machining results.

  Therefore, unless the exact same processing as the processing request is reproduced, the selected combination of processing conditions is not very likely. As a result, even if machining is performed with a combination of machining conditions close to the machining requirements, a desired machining result is often not obtained, and there is a possibility that a combination of machining conditions that leads to machining failure is set. Also, in order to be able to set the most appropriate combination of machining conditions as much as possible, it is necessary to prepare a huge number of machining data in advance, so it is necessary to perform a lot of test machining, The burden is heavy.

  In the case of the machining condition setting device disclosed in Patent Document 2, the number of combinations of machining conditions prepared for test machining can be relatively reduced. However, the combination of the machining conditions is such that each type of machining condition is closely related to each other, so that the machining conditions before the change are changed by changing and adjusting the specific type of machining conditions. A combination of machining conditions that produce unexpected machining results that are far from machining requests that cannot be predicted from the machining results in the combination is generated, which may cause machining failure.

  In addition, since one type of processing condition is operated, it is necessary to operate another type of processing condition, and thus it is difficult to reach an appropriate processing condition, and it may take a long time to set the processing condition. is there. In essence, since there is no change in extracting and setting a combination of machining conditions suitable for the machining request in relation to the whole machining condition combination and the machining result, in order to satisfy the reliability, in the end However, a database of combinations of machining conditions is required.

  In the case of the machining condition generation method disclosed in Patent Document 3, all types of machining condition combinations in which the parameter values of each type of machining condition in the selected combination of machining conditions are proportionally increased are used. Since the parameter values for machining requests do not necessarily increase or decrease proportionally, the parameter values for a specific type of machining request must be set between the machining request parameter values in a combination of machining conditions for multiple sets of machining conditions. Even if a combination is extracted and selected, it is not definitive whether the selected combination of machining conditions is a combination of machining conditions close to the combination of machining conditions to be generated. There is a risk of setting.

  In addition, since it is intended to generate machining conditions that match the machining requirements given from the combination of machining conditions prepared as basic data, essentially the relationship between the whole combination of machining conditions and the machining result. Therefore, in order to satisfy the reliability, a database of combinations of machining conditions is necessary in the end.

  In the case of the machining condition setting device disclosed in Patent Document 4, intermediate value data is obtained from the basic data according to the learning result, the machining current is set, and the machining conditions such as the on time and the off time are sequentially determined. There is no need to prepare machining data for a combination of machining conditions. In addition, since the machining current is set first, the possibility of machining failure is low and the reliability is improved. However, even if the intermediate value data of the representative data of the machining current value corresponding to the representative data of the machining demand in actual machining where the expected machining results are stably obtained, the machining efficiency is included. Whether optimum machining conditions for realizing better machining are set is not deterministic and there is room for improvement.

  Since the processing condition automatic selection device disclosed in Patent Document 5 determines the peak current value or the processing current value with respect to the desired processing surface roughness and then sequentially determines other types of processing conditions, There is no need to prepare machining data for the combination, and a reliable combination of machining conditions can be set. However, a combination of machining conditions is determined only by a theoretical correlation between a specific type of machining result and a specific type of machining condition, and there is sufficient theoretical correlation with other types of machining requirements or machining conditions. Therefore, machining results corresponding to machining requirements other than the desired machining surface roughness vary widely, resulting in a combination of machining conditions resulting in unexpected machining results that deviate greatly from the machining requirements. There is a fear.

  In particular, the side offset value in the first cut of sculpted EDM not only greatly affects the machining time of the entire machining, but also is limited by the electrode reduction amount. An appropriate combination of processing conditions is generated, and processing may fail. However, since there is no direct theoretical correlation between the specific type of machining conditions and the offset value, the specific type of machining conditions cannot be theoretically determined from the offset value, and the generated machining conditions It can only be guessed if the combination deviates from the electrode reduction. Therefore, there is room for setting a combination of machining conditions that are more excellent in machining efficiency, or it is necessary to generate a combination of repeated machining conditions, which may reduce the work efficiency.

  In view of the above problems, the present invention eliminates the need to prepare machining data for a combination of a large number of machining conditions, and by simply inputting a machining request, machining efficiency is high and reliable and safe initial machining. It is a main object to provide a machining condition setting device for die-sinking electric discharge machining that can set a combination of conditions more easily. The secondary object in the machining condition setting device of the present invention is specifically disclosed in accordance with the description of the machining condition setting device of the embodiment.

In order to solve the above-mentioned problems, the machining condition setting device of the present invention has an input device (1) for inputting a machining request that is information relating to machining indicating constraints in machining, and a plurality of types of parameters including the machining conditions and the machining request. Select a storage device (2) that stores multiple types of basic data indicating the theoretical correlation between them, and select a plurality of peak current values that can be obtained by first cut, and base each type of processing condition suitable for each peak current value. A plurality of sets of machining condition combinations are generated based on the data sequentially, and the basic side discharge gap is determined from the correlation between the on-time for each peak current value and the side discharge gap for each combination of machining conditions. And at least the correlation between the no-load voltage for each side discharge gap before correction and the side discharge gap after correction, during standby for discharge for each side discharge gap before correction The basic side surface discharge gap is corrected based on one or more of the correlation between the correction value and the corrected side surface discharge gap and the correlation between the processed depth for each side surface discharge gap before correction and the corrected side surface discharge gap. The surface discharge gap is calculated from the desired surface roughness and the machining surface roughness in each combination of machining conditions obtained based on the basic data, the corrected side surface discharge gap, and the side safety margin. The combination of machining conditions for each set of machining conditions is obtained based on basic data, and the combination of machining conditions to obtain the side offset value suitable for the electrode reduction amount input as the machining request is the first cutting machining condition combination. And an arithmetic unit (4) set as a combination.

  Preferably, the arithmetic device (4) selects a combination of machining conditions for obtaining an average machining current that can be taken with respect to a machining area from among a plurality of combinations of machining conditions generated. Further, the arithmetic device is characterized in that a combination of processing conditions for obtaining a side surface offset value having a value equal to or smaller than the electrode reduction amount and closest to the electrode reduction amount is set as a combination of first cut processing conditions.

  Preferably, the arithmetic device (4) is characterized in that a bottom surface offset value in a combination of processing conditions is obtained based on basic data. In particular, the arithmetic device (4) is characterized in that the feed amount in the machining depth direction in the first cut is obtained from the machining depth and the bottom surface offset value in the first cut.

  More preferably, the arithmetic unit (4) is configured to obtain a bottom surface offset in a combination of processing conditions from a processing surface roughness, a bottom surface discharge gap, and a bottom surface safety allowance in a combination of processing conditions obtained based on a desired processing surface roughness and basic data. It is characterized by obtaining a value.

  Desirably, the arithmetic unit (4) obtains a basic bottom surface discharge gap from the correlation between the ON time for each peak current value and the bottom surface discharge gap, and at least corrects the no-load voltage and the correction for each bottom surface discharge gap before correction. Correlation with the bottom discharge gap after correction, correlation between discharge standby time for each bottom discharge gap before correction and bottom discharge gap after correction, processing depth for each bottom discharge gap before correction and bottom discharge gap after correction The bottom surface discharge gap is obtained by correcting the basic bottom surface discharge gap from any one or more of the above correlations.

  Preferably, the arithmetic device (4) obtains the processing surface roughness in each processing step after the second cut based on the basic data from the desired processing surface roughness and the processing surface roughness in the combination of the processing conditions, A combination of processing conditions for each processing step is set for each processing step based on the surface roughness in each processing step.

  More preferably, the arithmetic unit (4) determines the peak current value based on the basic data from the processed surface roughness in the processing step in at least one processing step of each processing step, and each type of suitable for the peak current value. Processing conditions are sequentially determined based on basic data, and a combination of processing conditions is set. The computing device (4) is characterized in that a bottom surface offset value and a side surface offset value in each combination of machining conditions are obtained based on basic data.

  Desirably, the arithmetic unit (4) includes a machining surface roughness, a bottom surface discharge gap, a bottom surface safety allowance in a combination of a desired machining surface roughness and machining conditions obtained for each machining process based on basic data for each machining process. From each processing step, and the processing surface roughness, side discharge gap, and side surface in the combination of processing conditions of each processing step obtained based on the desired processing surface roughness and basic data for each processing step It is characterized in that the side surface offset value of each processing step is obtained from the safety allowance.

  Further, the arithmetic unit (4) obtains a basic bottom surface discharge gap from the correlation between the on-time for each peak current value and the bottom surface discharge gap, and at least the correlation between the no-load voltage and the bottom surface discharge gap to be corrected. The basic bottom surface discharge gap is corrected from one or more correlations between the discharge standby time and the bottom surface discharge gap to be corrected to obtain the bottom surface discharge gap of each processing step, and the peak current value The basic side discharge gap is obtained from the correlation between each on-time and the side discharge gap, and at least the correlation between the no-load voltage and the side discharge gap to be corrected, the discharge standby time and the side discharge gap to be corrected The side discharge gap of each machining step can be obtained by correcting the basic side discharge gap from any one or more of the correlations. The features.

  Desirably, the arithmetic unit (4) obtains the feed amount in the machining depth direction in each machining step from the bottom surface offset value in the preceding machining step and the bottom surface offset value in each machining step, and the side surface in the first cut. The rocking amount in each machining step is obtained from the offset value and the side surface offset value in each machining step.

  The reference numerals corresponding to the drawings attached to each device are given for convenience of explanation, and the configuration of the machining condition generation device of the present invention is the specific configuration of the machining condition generation device described in the embodiment. It is not limited to the exact same configuration.

  First, the machining condition setting device of the present invention generates a combination of machining conditions by sequentially determining each type of machining condition based on a plurality of types of basic data indicating a theoretical correlation between a plurality of types of parameters. Since the side offset value is obtained, the intermediate value data is not obtained, but the theoretical value data of each type of machining condition is obtained and a combination of the machining conditions is generated. Even if there is no processing record, a combination of safe processing conditions with high processing efficiency and high reliability is set.

  Secondly, the machining condition setting device of the present invention determines and sets a combination of machining conditions that will be a side surface offset value suitable for the electrode reduction amount from among a plurality of combinations of machining conditions that can be obtained by the first cut. Therefore, instead of determining a specific type of machining condition for a specific type of machining result and setting a combination of machining conditions, there is a theoretical correlation between multiple types of machining requirements and multiple types of machining conditions. Therefore, a combination of machining conditions is set with sufficient consideration, and a combination of safe machining conditions with high machining efficiency and high reliability is set.

  Thirdly, the processing condition setting device of the present invention theoretically obtains the side surface offset value of the generated combination of processing conditions, and sets the combination of processing conditions to obtain the side surface offset value suitable for the electrode reduction amount. Therefore, there is no risk of setting a combination of machining conditions that will result in a side offset value far from the electrode reduction amount, and a combination of machining conditions that will result in a side offset value closer to the electrode reduction amount will be set. It is possible to set a combination of machining conditions that are safe without failure and that are excellent in machining efficiency so that the machining time of the whole machining does not become unexpectedly long. Therefore, a combination of safe machining conditions with high machining efficiency and high reliability is set.

  At this time, the theoretically obtained side surface offset value has a certain amount of error in calculation. However, since the processing condition setting apparatus of the present invention calculates the side surface offset value theoretically, it is necessary to be able to obtain continuous parameter values having a theoretical correlation between each type of parameter. There is no need to prepare a large number of machining data depending on tolerances, as long as there is basic data with minimum representative data, and the reliability of the combination of set machining conditions is the same. If so, test processing can be greatly reduced, and the work burden is significantly reduced.

  Fourthly, the machining condition setting device of the present invention generates a combination of machining conditions by sequentially determining each type of machining condition including a peak current value, an on time, and an off time in a predetermined order. Compared with the method of extracting and setting the combination of machining conditions from the machining data in relation to the whole machining condition combination and machining requirements, there is a reliable and safe combination of machining conditions with no variation in machining results. It is sufficient to collect the minimum necessary representative data indicating the theoretical correlation between parameters, and it is not necessary to prepare a database of a huge number of processing condition combinations. This can greatly reduce the work burden.

  Fifth, the machining condition setting apparatus of the present invention can set safe machining conditions with high machining efficiency and high reliability simply by inputting data of machining requests by an operator. It is possible for a worker to easily set machining conditions with less risk of machining failure, and for a skilled worker, the time required for setting the machining conditions can be shortened, and the working efficiency is improved.

  Advantages obtained by the machining condition setting device of the present invention will be described in detail together with the action in accordance with the description of specific devices and components constituting the machining condition setting device in the embodiment.

  FIG. 1 is a block diagram showing the configuration of a preferred embodiment of the machining condition setting device of the present invention. The machining condition setting device according to the embodiment basically has the same configuration as a personal computer, and is provided in a computer numerical control device (CNC), but is connected to the numerical control device through a network. Can be provided.

  The machining condition setting device includes an input device 1, a first storage device 2, a second storage device 3, and an arithmetic device 4. FIG. 1 shows that the control device is limited to be used as a machining condition setting device, but it does not limit the operation of each device for purposes other than setting the machining conditions. Further, when the control device is used for purposes other than setting machining conditions including numerical control, another necessary device (not shown) can be provided in the control device.

  An input device 1 of a processing condition setting device includes an operation device such as a keyboard or a mouse, a disk drive that can read data from a storage medium such as a magnetic disk or an optical disk, and a USB flash memory that can import data from the outside ( It includes an external storage device such as a USB (Universal Serial Bus), a communication device capable of capturing data from a computer network such as a LAN adapter (LAN, Local Area Network), and a necessary input / output interface.

  The input device 1 is means for giving processing request data to the processing condition setting device. The input device 1 is means for inputting numerical data necessary when creating basic data. In FIG. 1, the processing request data input from the input device 1 is shown to be directly output from the input device 1 to the arithmetic device 4. However, when the processing request data is actually input, The data is temporarily stored in the first storage device 2 or the second storage device 3 by the arithmetic device 4 and read from the first storage device 2 or the second storage device 3 when necessary for the calculation.

  The processing request data is given as information on processing that is initially required in determining processing conditions as a parameter indicating processing constraints. The machining request may be a parameter of a machining result such as a desired machining surface roughness. The machining request is not limited to the case where the parameter value is directly input to the control device and is given, and may be obtained by being calculated from the parameter value which is not the machining request inputted to the control device.

  Machining requirements limit the machining conditions that can be used and also vary the machining results. Machining electrical discharge machining requirements include, for example, expected machining results such as desired surface roughness, tool electrode and workpiece materials, electrode reduction, machining area, machining depth, machining mode ( Machining shape) and liquid processing methods. In addition, the data of the processing form is not only data directly indicating the characteristics of the processing shape (contour shape of the processing hole) like a cylindrical shape or a cone shape, but also like rib processing, gate processing, core pin processing, etc. It is a collective term including data that indirectly indicates the features of the processed shape.

  The types of machining conditions to be set differ depending on the specifications of the machine main unit and the machining power supply device. Therefore, the following description will be made on typical electric conditions such as peak current value, on time, off time, servo reference voltage, polarity, and no-load voltage. Further, the processing request will be described by limiting to parameters necessary for determining the above-described processing conditions or calculating the offset value. At this time, it is not necessary to determine all kinds of machining conditions one by one based on the basic data in the combination of machining conditions. Depending on the kind of machining conditions, Various types of processing conditions can be determined simultaneously.

  In the machining condition setting apparatus of the embodiment, at least a desired machining surface roughness, tool electrode and workpiece material, and electrode reduction amount (electrode reduction allowance) are input as machining requests. Also input the machining area and machining depth. The processing area may be any of an electrode projection area, an electrode surface area, and a bottom area of the processing hole. The processing area and the processing depth are calculated by the arithmetic device 4 by inputting the dimensions of the machining hole and the tool electrode, instead of the operator directly inputting the parameter values from the input device 1 as the machining request data. To the machining condition setting device. Further, the machining area and the machining depth can be obtained by calculation from solid data by inputting the three-dimensional shape data (solid data) of the workpiece shape (machining shape) and the tool electrode shape.

  The first storage device 2 is an auxiliary storage device that stores data such as a large-capacity hard disk drive. As the first storage device 2, a disk drive device that reads / writes data from / to a storage medium such as a magnetic disk or an optical disk can be used. Also, an external storage device such as a USB flash memory may be used, and there is no limitation as long as the basic data can be stored even while the power is turned off.

  The first storage device 2 is means for storing a plurality of types of basic data. The first storage device 2 stores data of parameters that are initially given in the process of determining the machining conditions as necessary. Specifically, the first storage device 2 stores in advance a plurality of peak current values that can be obtained by first cutting for each material of the tool electrode and the workpiece in combination with corresponding no-load voltage and polarity data. ing. When the machining condition setting device has a database in which a plurality of combinations of machining conditions are registered, the data of a plurality of peak current values need not be newly created, and an existing database can be used. .

  The basic data is data of the parameter value of the other parameter (hereinafter referred to as the dependent parameter) having a theoretical correlation with the parameter value of the parameter of one type (hereinafter referred to as the principal parameter). It is the data which collected. Therefore, the basic data shows a theoretical correlation between a plurality of types of parameters. The plural types of parameters having a theoretical correlation include machining conditions and machining requirements.

  The theoretical correlation between multiple types of parameters is not limited to cases where there is a direct causal relationship between multiple types of parameters. This includes the case where a correlation is found that affects and determines the parameter value of the dependent parameter. Therefore, the basic data in the present invention is not an accumulation of parameter values of a plurality of parameters that have at least a theoretical correlation or a simple collection of machining data in which machining conditions and machining results are combined. When the value is determined, the parameter value of the corresponding dependent parameter is determined within a predetermined error range. Therefore, the parameter value of the dependent parameter corresponding to the parameter value of the main parameter obtained from the basic data is a theoretically correct value and has high reliability.

  The plurality of types of basic data are stored in the first storage device 2 in the form of a data file given arbitrary data file names. The basic data that shows the theoretical correlation of multiple types of parameters is not only the data that shows the correlation between multiple types of parameters in physical formulas or chemical formulas, but also the processing results expected in actual processing. Data that is theoretically correlated by experience, such as sample data.

  Basic basic data is a collection of representative data with deterministic parameter values including sample data from which the expected machining results are obtained in actual machining with multiple types of parameters that have a theoretical correlation. is there. Basic basic data is not data in which representative data is collected in a discrete manner, but can be expressed as a continuous parameter value with an appropriate approximate expression within a range that does not deviate from the theory and accuracy in the correlation of multiple types of parameters. It is data. Therefore, the basic data may include data of approximate expressions expressed as continuous parameter value data of a plurality of types of parameters having a theoretical correlation by aggregating a plurality of representative data. The basic data including the approximate expression can represent a theoretical correlation between the main parameter and the dependent parameter with a line graph.

If the basic data contains approximate expression data that forms continuous parameter value data from representative data based on the theoretical correlation between multiple types of parameters, parameter values that do not exist in the representative data When given, it is possible to always obtain the theoretical value of the subordinate parameter corresponding to the parameter value of the main parameter , not just the intermediate value data. In addition, since it is only necessary to provide a number of representative data that can obtain a continuous parameter value based on the theory within a practically acceptable error range, when generating basic data based on machining data, It has the advantage that reliable basic data can be created with few test processes.

  In practice, basic data regarding parameters that do not require an intermediate value has a theoretical correlation with a representative parameter value of a principal parameter or a principal parameter corresponding to a parameter value in a predetermined range on a one-to-one basis. It is an accumulation of data consisting of parameter values of dependent parameters or parameter values within a predetermined range. Such basic data can be represented by a correspondence table indicating the correlation between the subject parameter and the dependent parameter.

  The plurality of types of basic data stored in the first storage device 2 can be edited by changing, deleting, and adding numerical values of representative data including sample data. As a result, it is possible to improve the accuracy of the basic data and evolve the error of the parameter value to be output. In addition, it is possible to select and change the type of approximate expression capable of obtaining continuous parameter value data having a theoretical correlation from representative data with definite parameter values including sample data. As a result, basic data can be easily reconstructed based on a new theory.

  The first storage device 2 can store a combination of machining conditions generated by a program that generates a combination of machining conditions. The combination of processing conditions stored in the first storage device 2 can be stored in a storage medium through a disk drive device or stored in a USB flash memory through a USB port. The processing condition combination data stored in the first storage device 2 can be registered by adding a processing condition number to an existing processing condition database.

  The second storage device 3 is a temporary storage device such as a volatile memory (RAM, Random Access Memory) used for calculation. The second storage device 3 may be any storage device that can temporarily store data that can exchange data with the arithmetic device 6 at high speed.

  The second storage device 3 includes machining request data input from the input device 1, data of a combination of one or more machining conditions generated by the computing device 4, and a machining surface roughness obtained by computation of the computing device 4. Further, it is means for storing calculation result data such as a discharge gap and an offset value and data necessary for the calculation of the calculation device 4.

  The arithmetic device 4 is a central processing unit (CPU). The arithmetic device 4 determines a plurality of types of machining conditions in a predetermined order based on the basic data, generates a combination of machining conditions, and is requested from the generated plurality of combinations of machining conditions. This is a means for selecting and setting a combination of processing conditions that provides an optimum side surface offset value for the electrode reduction amount.

  The computing device 4 has one or more peaks that can be taken by the first cut stored for each material of the tool electrode and the workpiece based on the material of the tool electrode and the workpiece inputted from the input device 1 as the machining request. Current value data is selected and read from the first storage device 2. In the embodiment, the arithmetic device 4 extracts the peak current value by data combining the no-load voltage corresponding to the peak current value and the polarity. Therefore, even if the peak current value is the same value, if the corresponding no-load voltage and the polarity are different, they are read as different data.

  The arithmetic device 4 is configured to output each peak current for each of one or more peak current values that can be taken by the first cut selected based on the tool electrode read from the first storage device 2 and the material of the workpiece. Each type of machining condition including on time and off time suitable for the value is sequentially determined based on basic data in a predetermined order, and one or more combinations of machining conditions are candidates for machining condition combinations in the first cut Generate.

  The computing device 4 obtains the side surface offset values in the combinations of the plurality of processing conditions generated as candidates based on the basic data. Specifically, the side surface offset value is a processing surface roughness in a combination of a desired processing surface roughness input from the input device 1 as a processing request and processing conditions of each set obtained based on basic data, a side discharge gap, It is required from the side safety fee.

  At this time, it is possible to calculate the side surface offset value in consideration of the electrode consumption amount by obtaining the electrode consumption amount based on the basic data. However, the amount of electrode wear varies depending on the machining depth position corresponding to the machining shape, so if the machining depth position for calculating the electrode wear amount is not specified correctly, the electrode wear amount will be at a certain machining depth position. May cause a failure in processing.

  However, it is difficult to accurately specify the machining depth position for calculating the electrode consumption corresponding to the machining shape in the case of a complicated machining shape at the current technical level. Further, the difference in the processing time caused by the error of the side surface offset value obtained without considering the electrode consumption amount is a little of the entire processing time, and therefore hardly affects the processing efficiency. For this reason, in the machining condition setting apparatus according to the embodiment, for safety, the side surface offset value is calculated while ignoring the electrode consumption.

  The arithmetic device 4 compares the side offset value in each candidate combination of processing conditions with the electrode reduction amount input from the input device 1 as a processing request in order, and calculates a side offset value suitable for the electrode reduction amount. A combination of processing conditions to be obtained is set as a combination of processing conditions for the first cut. The optimum combination of machining conditions to be selected is a combination of machining conditions for obtaining a side offset value having a value not more than the electrode reduction amount and the closest value. Therefore, a combination of processing conditions that does not fail in processing and that has higher processing efficiency is set.

  The arithmetic device 4 extracts a combination of machining conditions having an average machining current value that can be taken with respect to the machining area input as a machining request from the combinations of the machining conditions, and extracts the combinations of the machining conditions thus extracted. Thus, a combination of processing conditions for obtaining a side surface offset value suitable for the electrode reduction amount is selected. The average machining current value can be calculated from the peak current value, the on time, and the off time. For this reason, combinations of machining conditions having a combination of an inappropriate peak current value, an on time, and an off time resulting in an unacceptable machining speed corresponding to the machining area are eliminated. Therefore, it is beneficial in that the risk of setting an inappropriate combination of processing conditions is smaller.

  The computing device 4 is configured to obtain the machining surface roughness, the side surface discharge gap, and the side surface safety allowance based on basic data. Therefore, the calculated side offset value is a theoretical value obtained by calculation, not an intermediate value estimated from the machining data gathered from the machining results, and it was obtained by chance as a machining result. Inappropriate side offset values are eliminated. Further, it is possible to theoretically obtain a side surface offset value that does not have a direct theoretical correlation with the entire combination of machining conditions. As a result, it is possible to determine a combination of machining conditions that has no variation in machining results and has high reliability.

  The size of the discharge gap can be roughly estimated from the discharge energy. The magnitude of the discharge energy is greatly affected by the peak current value and the on-time. Therefore, the arithmetic device 4 calculates | requires a side discharge gap from the correlation of the ON time for every peak electric current value, and a side discharge gap.

  In actual machining, the discharge gap varies depending on several factors. Therefore, in the machining condition setting device of the embodiment, the arithmetic device 4 has several factors (parameters) that affect a discharge gap that is already known as a basic discharge gap based on the discharge gap obtained based on the discharge energy. Is to be corrected by. Therefore, the machining condition setting device of the embodiment has an advantage that the side surface discharge gap value can be accurately estimated and the side surface offset value can be obtained more accurately.

  Parameters affecting the side discharge gap include, for example, no-load voltage, an unspecified delay time from when a voltage is applied to the machining gap until discharge occurs (discharge standby time, no-load time, discharge delay time), There is processing depth. The arithmetic unit 4 corrects the basic side surface discharge gap based on one or more basic data for correcting the basic side surface discharge gap obtained based on the discharge energy to obtain a final side surface discharge gap. Basic data for correcting the basic discharge gap is stored in the first storage device 2 together with other types of basic data.

  Specifically, the arithmetic unit 4 corrects the basic side discharge gap based on basic data indicating the correlation between the no-load voltage for each side discharge gap before correction and the corrected side discharge gap. Next, the side discharge gap corrected by the no-load voltage is corrected based on the basic data indicating the correlation between the discharge standby time for each side discharge gap before correction and the corrected side discharge gap. Then, the side discharge gap corrected by the discharge standby time is corrected based on basic data indicating the correlation between the processing depth for each side discharge gap before correction and the corrected side discharge gap.

  Moreover, the arithmetic unit 4 calculates | requires the bottom face offset value of the 1st cut in the combination of the process conditions set based on basic data. Similar to the side surface offset value, the bottom surface offset value is obtained from the desired surface roughness and the surface roughness, bottom surface discharge gap, and bottom surface safety allowance in each combination of processing conditions obtained based on basic data. . For this reason, the obtained bottom surface offset value is a theoretical value from which an inappropriate value obtained by chance is eliminated, so that a combination of machining conditions having high machining results without variation can be determined.

  In the machining condition setting device according to the embodiment, the bottom surface offset value in each combination of machining conditions is obtained before determining the combination of the first cut machining conditions. However, the bottom surface offset value is different from the side surface offset value limited by the electrode reduction amount, and can be adjusted by changing the feed amount. Therefore, the bottom surface offset value is obtained after the combination of the first cut processing conditions is selected and set. Can be.

  Similar to the side discharge gap, the basic bottom discharge gap obtained based on the discharge energy is obtained from basic data indicating the theoretical correlation between the ON time for each peak current value and the side discharge gap. The basic bottom surface discharge gap obtained based on the discharge energy is corrected by a parameter that affects the bottom surface discharge gap, so that the bottom surface offset value can be obtained more accurately. Parameters affecting the bottom discharge gap include, for example, no-load voltage, discharge standby time, and machining depth.

  Specifically, the arithmetic device 4 corrects the basic bottom surface discharge gap based on basic data indicating the correlation between the no-load voltage for each bottom surface discharge gap before correction and the bottom surface discharge gap after correction. Next, the bottom discharge gap corrected with the no-load voltage is corrected based on the basic data indicating the correlation between the discharge standby time for each bottom discharge gap before correction and the bottom discharge gap after correction. Then, the bottom discharge gap corrected by the discharge standby time is corrected based on the basic data indicating the correlation between the processing depth for each bottom discharge gap before correction and the bottom discharge gap after correction.

  For the combination of the machining conditions of the machining process after the second cut, the arithmetic unit 4 determines whether the machining surface roughness in each machining process is based on the desired machining surface roughness and the machining surface roughness in the combination of the first cut machining conditions set based on the basic data. The machining surface roughness is obtained, and a combination of machining conditions is set for each machining process from the machining surface roughness in each machining process.

  The processing condition setting device of the present invention configured as described above is limited by the electrode reduction amount, varies depending on the combination of processing conditions, and has a direct theoretical correlation with the entire combination of processing conditions. The side offset value in the first cut that has not been performed can be obtained theoretically, so it is not affected by variations in machining results, and the machining efficiency optimal for the electrode reduction amount given as the machining request is high and reliable. A combination of safe first cut processing conditions can be set more easily.

  In addition, since the machining condition setting device of the present invention sequentially determines a plurality of types of machining conditions based on basic data consisting of a small amount of representative data at least in the first cut, the side surface offset is within an allowable error range. It is not necessary to prepare enormous combinations of processing conditions so as to precisely correspond to the value or the electrode reduction amount. Therefore, test processing can be greatly reduced, and the work burden is reduced.

  As already explained, in order to obtain the desired machining surface roughness finally required in the final finishing machining process, the discharge energy is gradually reduced in each machining process to reduce the machining surface roughness. Therefore, when the combination of the cutting conditions for the first cut is determined, the combination of the processing conditions for the processing steps after the second cut is finally required to be the surface roughness in the combination of the cutting conditions for the first cut. It can be obtained with the processed surface roughness of each processing step determined by the desired processed surface roughness. Therefore, even if the combination of the processing conditions in each processing step after the second cut is extracted from the database based on the processing surface roughness and set, the sufficient benefits of the present invention can be obtained.

  In the processing condition setting device according to the embodiment, the arithmetic device 4 has processing conditions suitable for processing requirements in relation to the overall combination of processing conditions and processing results even in at least one processing step of each processing step after the second cut. Instead of extracting and setting a combination, each type of machining condition is theoretically determined in order, and a combination of machining conditions is generated and set. Specifically, the arithmetic unit 4 sequentially determines a plurality of types of processing conditions including on-time and off-time based on basic data for each processing step after the second cut in a predetermined order, and combines the processing conditions. Set.

  Therefore, the combination of machining conditions in the intermediate finishing process after the second cut, which has a relatively small variation but affects the machining time, is theoretically generated. There is an advantage that it is possible to more easily set a combination of processing conditions that are more stable and excellent in processing efficiency close to processing requirements.

  Further, the arithmetic device 4 is configured to obtain a bottom surface offset value and a side surface offset value in a combination of processing conditions of each processing step based on basic data. In particular, the arithmetic unit 4 determines each processing step based on the processing surface roughness, the side discharge gap, and the side safety allowance in the combination of processing conditions of each processing step obtained based on the desired processing surface roughness and basic data. The bottom face offset value and the side face offset value of the machining process are obtained. For this reason, an appropriate offset value is theoretically obtained for the combination of the processing conditions of each processing step, and the feed amount and the swing amount with high reliability, safety, and processing efficiency can be determined.

  The basic side surface discharge gap and bottom surface discharge gap obtained based on the discharge energy in the machining process after the second cut are obtained from the correlation between the ON time and the discharge gap for each peak current value. Further, the basic discharge gap obtained based on the discharge energy is corrected by a parameter that affects the discharge gap. Parameters affecting the discharge gap in the machining process after the second cut include, for example, no-load voltage and discharge standby time.

  Specifically, the arithmetic device 4 corrects the basic discharge gap obtained based on the discharge energy based on the basic data indicating the correlation between the no-load voltage for each discharge gap before correction and the discharge gap after correction. . Next, the bottom surface discharge gap corrected with the no-load voltage is corrected based on the basic data indicating the correlation between the discharge standby time for each discharge gap before correction and the discharge gap after correction. The process for determining the side discharge gap and the bottom discharge gap is the same, but the basic data used is different.

  The arithmetic unit 4 obtains the feed amount in the machining depth direction in the first cut from the machining depth input from the input device 1 as the machining request and the bottom surface offset value in the first cut. Further, the arithmetic device 4 obtains the feed amount in the machining depth direction in each machining process from the bottom surface offset value in the previous machining process and the bottom surface offset value in each machining process, and is input from the input device 1 as a machining request. The amount of oscillation in each processing step is obtained from the electrode reduction amount and the side surface offset value in each processing step. The relationship between the parameters is shown in FIGS. 10 and 11, and the description of FIGS. 10 and 11 is referred to.

  Therefore, from the first cut to the final finish machining process based on the offset value theoretically calculated, not the offset value estimated from the mere machining data obtained separately based on the machining results in actual machining Therefore, it is possible to automatically determine a safe feed amount and swing amount which are suitable for the combination of the machining conditions and have high machining efficiency and high reliability. As a result, creation of the NC program becomes easier.

  Below, the structure of the arithmetic unit 4 is demonstrated concretely. The machining condition generating unit 41 stores one or more peak current values that can be obtained by different first cuts depending on the material of the tool electrode and the workpiece in the first storage device 2 for each material of the tool electrode and the workpiece. Select from multiple peak current data and read.

  The machining condition setting device according to the embodiment assumes a machining power supply device for a sculpting electric discharge machining device configured to set a peak current value by the number of connected switching circuits connected in parallel. Therefore, the no-load voltage needs to be specified in order to calculate the real value of the peak current value. Moreover, since the parameter value in the correlation of each type of processing conditions differs depending on the polarity, it is necessary to select and specify basic data to be used for each polarity. Therefore, the peak current value data that can be obtained by the first cut stored in the first storage device 2 is stored as a combination of no-load voltage and polarity, and the arithmetic device 4 can obtain the peak current that can be obtained by the first cut. Data of a combination of value, no-load voltage and polarity is read out.

  The processing condition generation unit 41 determines an on time for the selected peak current value based on basic data indicating a theoretical correlation between the peak current value and the on time. If the wear of the tool electrode is not taken into consideration, the on-time can be determined by a theoretical correlation between the peak current value at which the maximum machining speed is obtained and the on-time. When the consumption of the tool electrode is taken into consideration, the on-time for the peak current value at which the required electrode consumption ratio or machining speed is obtained is determined in consideration of the electrode consumption ratio and the machining speed.

  As shown in FIG. 2, basic data indicating the theoretical correlation between the peak current value at which the maximum machining speed is obtained and the on time, and the peak current value at which the minimum electrode wear ratio (electrode no wear) is obtained and on The range of the on-time with respect to the peak current value can be determined based on basic data indicating a theoretical correlation with time. Then, as shown in FIG. 3, the range of the electrode wear ratio with respect to the range of the on time previously determined based on the basic data indicating the theoretical correlation between the on time for each peak current value and the electrode wear ratio. Can be determined.

  As shown in FIG. 4, the processing condition generation unit 41 determines the consumption ratio importance ratio based on basic data indicating a theoretical correlation between the peak current value and the consumption ratio importance ratio (consumption ratio importance degree). Then, the electrode consumption ratio is obtained from the consumption ratio weight ratio with respect to the previously determined electrode consumption ratio range, and the ON time for the required electrode consumption ratio is determined based on the basic data shown in FIG.

  The consumption ratio importance ratio is a parameter that indicates how much importance is attached to reducing the consumption of the tool electrode in percentage. FIG. 3 shows the on-time when the minimum electrode consumption ratio (no electrode consumption) is obtained when the consumption-oriented ratio is 100%, and shows the on-time when the maximum machining speed is obtained when the consumption-oriented ratio is 0%. When the consumption ratio weight ratio is given as a numerical value as a processing request, the on-time is determined without obtaining the consumption ratio weight ratio. Further, in machining that does not require the consumption of the tool electrode, this is the on-time when the consumption ratio weighted ratio is 0%.

  Since the processing speed and the electrode consumption ratio are in a contradictory relationship, the on-time can be determined using the processing speed and the processing speed priority ratio as parameters instead of the electrode consumption ratio and the consumption ratio priority ratio. . The basic data used at this time are the basic data that shows the theoretical correlation between the on-time for each peak current value and the machining speed, and the basic data that shows the theoretical correlation between the peak current value and the machining speed priority ratio. It is.

  Since the off time is a time during which machining is not performed, if the off time is too long, the machining speed becomes slow. The off time is a period during which the machining gap is deionized. If the off time is too short, the occurrence rate of defective discharge that adversely affects machining such as arc discharge increases. The longer the on-time, the longer the time required for insulation recovery. Therefore, it is necessary to lengthen the off-time. Therefore, as shown in FIG. 5, the machining condition generation unit 41 determines the off time based on basic data indicating a theoretical correlation between the on time and the off time.

  The servo reference voltage can be calculated by dividing the sum of the product of the discharge standby time and the no-load voltage, the on time, and the machining voltage by the sum of the on time and the non-discharge time. The machining voltage is a discharge voltage when a normal discharge that contributes to machining occurs and a discharge current is supplied. The non-discharge time is a time during which no discharge is performed, and is the sum of the discharge standby time and the off time. The discharge standby time is unspecified and varies in single discharge, but if there is an actual measurement value, the average non-discharge time in a specific period with respect to the on-time can be obtained relatively accurately. For this reason, the discharge standby time is obtained by obtaining the non-discharge time based on the basic data indicating the theoretical correlation between the on-time and the non-discharge time and subtracting the off-time from the non-discharge time. The machining voltage is set to a specific value for each material of the tool electrode and the workpiece.

  From this, the machining condition generating unit 41 theoretically obtains the discharge standby time and the machining voltage based on the basic data, and determines the determined discharge standby time and machining voltage, the already determined on time, off time, Servo reference voltage is determined from no-load voltage.

  The machining condition generation unit 41 determines a peak current value and an on-time in each machining process after the second cut based on the machining surface roughness obtained by the machining surface roughness inference unit 42. Specifically, the machining condition generation unit 41 determines a peak current value corresponding to the machining surface roughness of the machining process obtained in advance by the machining surface roughness inference unit 42 and determines the determined peak current. The on-time corresponding to the value is obtained.

  The machining condition generation unit 41 determines each type of machining condition including the off time in a predetermined order in the same manner as the first cut. The basic data used when determining each type of processing condition is basic data having the same parameter type and a different parameter value having a theoretical correlation with the first cut. The generated combination of processing conditions is temporarily stored in the second storage device 3.

  The machining surface roughness inference unit 42 uses the machining surface roughness in the combination of one or more candidate machining conditions in the first cut generated by the machining condition generation unit 41 as basic data stored in the first storage device 2. Infer based on. Specifically, the machined surface roughness in a specific combination of machining conditions can be theoretically obtained based on basic data indicating the correlation between the ON time for each peak current value and the machined surface roughness. The inferred machining surface roughness in the first cut is stored in the second storage device 3.

  The machined surface roughness inference unit 42 is a desired machined surface which is the final finished surface roughness input from the input device 1 as the machined surface roughness and machining request data in the first cut stored in the second storage device 3. Based on the basic data indicating the correlation between the surface roughness in the previous machining step and the surface roughness in the next machining step so that the first cut surface roughness is gradually reduced from the roughness. To determine the surface roughness of each processing step.

  The machining surface roughness inference unit 42 generates basic data indicating a correlation between the machining surface roughness in the next machining process and the machining surface roughness in the next machining process after the combination of machining conditions in each machining process is generated. In addition to the machined surface roughness obtained based on this, the machined surface roughness is re-inferred based on basic data indicating the correlation between the ON time for each peak current value and the machined surface roughness. The basic data used for the calculation at this time is the same data as the basic data used when calculating the surface roughness in the first cut, but the parameter values are different, and the basic data used in the first cut is Another basic data.

  The discharge gap inference unit 43 infers a discharge gap in a combination of one or more machining conditions that can be taken by the first cut generated by the machining condition generation unit 41 based on basic data stored in the first storage device 2. . The side discharge gap and the bottom discharge gap are inferred based on different basic data. As described above, the discharge gap is basically obtained based on basic data indicating the correlation between the ON time for each peak current value and the discharge gap, and is corrected by a plurality of types of parameters that cause fluctuations in the discharge gap. . The inferred discharge gap is temporarily stored in the second storage device 3.

  When correcting the basic discharge gap obtained based on the discharge energy, the correction value is obtained in advance, and then the basic discharge gap is comprehensively corrected by a plurality of obtained correction values. be able to. Since the influence on the discharge gap may be slight, it is not necessary to correct the basic discharge gap with all kinds of parameters that cause variations in the discharge gap. Also, the basic discharge gap can be corrected with other types of parameters that can affect the discharge gap, such as, for example, liquid processing methods.

  The discharge gap inference unit 43 can infer the discharge gap in the combination of the machining conditions of the machining process after the second cut by the same method as the first cut. However, the basic data used for the calculation at this time is the same data as the basic data used when calculating the discharge gap in the first cut, but the parameter values are different, and the basic data used in the first cut is Another basic data. Further, different basic data are used for the side surface discharge gap and the bottom surface discharge gap.

  The offset value calculation unit 44 reads out the desired machining surface roughness, which is the final finished surface roughness stored in the second storage device 3, and the machining surface roughness and the discharge gap in the combination of the machining conditions. The safety factor is calculated based on basic data that shows a theoretical correlation with the safety factor that determines how much safety allowance should be taken for the surface roughness, and the safety factor is multiplied by the safety factor. Then, the machining surface roughness, the discharge gap, and the safety allowance are added, and then the desired machining surface roughness is subtracted to obtain the offset value. The calculation of the offset value is performed for each processing step for each of the side surface and the bottom surface.

  The machining condition setting unit 45 has an average machining current value suitable for the machining area from among candidate machining condition combinations generated for each peak current value that can be taken in the first cut stored in the second storage device 3. A combination of processing conditions is extracted. Then, the machining condition setting unit 45 compares the side surface offset value in the combination of the extracted machining conditions with the electrode reduction amount input from the input device 2 and stored in the second storage device 3. The combination of the processing conditions of the side surface offset value closest to the electrode reduction amount equal to or less than the electrode reduction amount is output as the first cut processing condition.

  Further, the machining condition setting unit 45 reads a combination of machining conditions in each machining process after the second cut stored in the second storage device 3 and sets it as a machining condition in each machining process. The set combination of machining conditions for each machining step is temporarily stored in the second storage device 3. The combination of the machining conditions of each machining process stored in the second storage device 3 can be stored in the first storage device 2 in accordance with the machining request by assigning a machining condition number.

  The arithmetic unit 4 calculates the feed amount in the machining depth direction in the first cut from the machining depth and the bottom surface offset value in the first cut. Further, the feed amount in the machining depth direction in the next processing step is sequentially obtained from the bottom surface offset value in the previous processing step and the bottom surface offset value in the next processing step. Further, the swing amount in each processing step is obtained from the electrode reduction amount and the side surface offset value in each processing step. A movement command value in each axis direction is calculated based on the obtained feed amount and swing amount. Therefore, since an appropriate and highly reliable feed amount and swing amount can be obtained, there is no machining failure, a desired machining time can be obtained, and machining efficiency is improved.

  As described above, the processing condition setting device according to the embodiment is generated using the basic data after generating a combination of a plurality of processing conditions according to the processing conditions that can be obtained by the first cut regardless of the processing result. The machining results in each set of machining conditions are theoretically obtained, and a combination of machining conditions meeting the machining requirements is determined and set from a plurality of sets of machining condition combinations.

  Therefore, a method of extracting and setting the entire combination of machining conditions corresponding to a specific type of machining request as one data or determining a specific type of machining condition for a specific type of machining result, and sequentially starting from the specific type of machining condition. It is possible to set a combination of processing conditions for obtaining a side surface offset value closer to the electrode reduction amount with less processing data than a method of determining the types of processing conditions. As a result, the processing efficiency can be improved and there is no risk of processing failure. In addition, it is not necessary to prepare a large amount of sample data, and the burden of work by test processing is greatly reduced.

  Hereinafter, a process for setting machining conditions by the machining condition setting apparatus according to the embodiment will be described with reference to flowcharts shown in FIGS. FIG. 6 shows a process for generating a combination of machining conditions from peak current values that can be obtained by the first cut.

  When generating a combination of machining conditions in the first cut, first, based on the data of the combination of the tool electrode and the material of the workpiece, which is the machining request data stored in the second storage device 3, the first The peak current value data that can be obtained by the first cut is read out from the tool electrode and the peak current value data for each material of the workpiece stored in the storage device 2 and stored in the second storage device 3 (S1). .

  In the control device of the EDM apparatus in the embodiment, the peak current value data is not configured to be set as a real value, so the no-load voltage is specified in calculating the real value of the peak current value. Further, since the correlation of parameters for determining the on time and the off time differs depending on the polarity, the peak current value data is stored in a combination of no-load voltage and polarity. Therefore, even if the peak current value is the same, all data having different combinations of no-load voltage and polarity are read as different data.

  In the case of a machining power supply apparatus configured to control the peak current value by the number of switching circuits connected in parallel, the number of peak current values that can be set is determined by the number of combinations that connect the switching circuits. When the power supply voltage of the machining DC power supply is switchable, the set no-load voltage is determined by the number of power supply voltages that can be switched. There are two types of polarity: positive electrode and negative electrode. Therefore, in the embodiment, the number of read peak current values is limited to an appropriate number.

  Even in the case of a machining power supply device that can change the peak current value and no-load voltage to analog, it is basically set with parameter values that are uniquely defined by the controller, not real values. Therefore, the number of data of the peak current value read out is limited to an appropriate number. If the processing power supply device has a configuration in which the number of peak current values is not limited, the number of peak current value parameter data stored in advance for each tool electrode and workpiece may be limited. Good.

  As described above, the parameter given first when determining the combination of the cutting conditions of the first cut is the peak current value, but there is no limitation except that the given parameter value can be taken by the first cut. If there is an existing database that is integrated, the existing database can be used to extract the peak current value and the no-load voltage and polarity data corresponding to the peak current value. There is no need to prepare data separately.

  Next, the on-time is determined from a theoretical correlation between the peak current value and the on-time. In the first cut, machining with the shortest possible machining time is the most efficient, so if there is no restriction on the electrode wear ratio, the maximum machining speed can be obtained for the on time to be set. This is the on-time for the peak current value. Therefore, the on-time with respect to the peak current value can be determined based on the basic data showing the theoretical correlation between the peak current value and the on-time at which the maximum machining speed is obtained.

  The machining speed increases because the amount of discharge per discharge increases as the discharge energy per discharge increases. Since the discharge energy per discharge is proportional to the discharge current value of the discharge current pulse, it tends to increase as the peak current value increases and the on-time increases. However, since electric discharge machining is performed by repeatedly generating electric discharge, the machining efficiency is lowered when the discharge repetition frequency is lowered. Therefore, there is an upper limit of the on-time. FIG. 2 shows the correlation of the on-time with the peak current value obtained by approximating typical data in actual machining in which the machining result expected based on this theory is stably obtained by an approximate expression. An example of the maximum machining speed curve is shown.

  Here, in actual electric discharge machining, in the case of machining with a relatively high peak current value in machining of a bottomed hole, an electrode consumption ratio that requires a certain degree of machining efficiency is required. For example, if the machining time is shortened by increasing the machining speed, the wear of the tool electrode is increased, and the remaining amount is increased accordingly. For this reason, the machining allowance after the next machining step for machining with a smaller discharge energy is increased, which may be longer from the machining time required for the entire machining. Alternatively, if the consumption of the tool electrode is ignored in a machining process in which machining is performed at a relatively large peak current value, there is a possibility that an extra number of tool electrodes may be required. Therefore, an optimum on-time for the peak current value is determined in consideration of the electrode consumption ratio.

  First, as shown in FIG. 2, basic data indicating the theoretical correlation between the peak current value at which the maximum machining speed is obtained and the on-time, and the peak current value at which the minimum electrode wear ratio (electrode no wear) is obtained. A range of the on-time with respect to the selected peak current value is determined based on basic data indicating a theoretical correlation between the on-time and the on-time.

  It is known that when the tool electrode is graphite or copper and the work piece is iron, supplying a discharge current pulse longer than a certain ratio to the peak current value, that is, a so-called long pulse, reduces the electrode consumption ratio. As the ON time is longer, the electrode consumption ratio tends to be smaller. Therefore, next, as shown in FIG. 3, the peak current obtained by approximating representative data in actual machining in which the machining result expected based on this theory is stably obtained by an approximate expression. The range of the electrode wear ratio with respect to the previously determined on time range is determined based on the basic data indicating the theoretical correlation between the on time and the electrode wear ratio for each value (S2).

  When the electrode consumption ratio is not given as a processing request, the peak current value selected based on the basic data indicating the theoretical correlation between the peak current value and the consumption ratio weighted ratio as shown in FIG. Determine the ratio of consumption ratio emphasis. The consumption ratio weighted ratio means that the larger the numerical value, the smaller the electrode consumption ratio is required. Basically, the machining area where the peak current value is large when the on-time is the same, the greater the wear of the tool electrode, and the larger the machining allowance, the greater the machining error. It can be said that there is. Based on this theory, a consumption ratio weight ratio with respect to the peak current value as shown in FIG. 4 is given.

  When the consumption ratio weighted ratio is given as a numerical value as a processing request, it is not necessary to obtain it based on basic data. In addition, for example, “consumption without electrode”, “low consumption with electrode”, “consumption with electrode”, “emphasis on consumption”, “standard”, “emphasis on speed” is given an ambiguous importance on consumption as processing requirements. In such a case, the consumption ratio weighted ratio is obtained according to a predetermined rule.

  When the wear ratio weight ratio is obtained, the upper limit of the electrode wear ratio is 0%, and the lower limit of the electrode wear ratio is 100%. The electrode consumption ratio is obtained by the ratio (S3). Once the electrode wear ratio is obtained, the on time with respect to the electrode wear ratio can be determined based on the basic data indicating the theoretical correlation between the on time for each peak current value and the electrode wear ratio shown in FIG. (S4).

  At this time, since the electrode consumption ratio and the processing speed are basically in a contradictory relationship, the on-time can be determined by the processing speed and the processing speed priority ratio instead of the electrode consumption ratio and the consumption ratio priority ratio. . In addition, when the maximum processing speed is required, the consumption ratio priority ratio is 0%, and when the lowest electrode consumption ratio is required, the consumption ratio priority ratio is 100%, which is shown in FIG. The on-time for the peak current value can be determined from the maximum processing speed curve or the minimum electrode consumption ratio curve.

  The off time is a time required for deionization of the processing gap, and the longer the on time, the longer the deionization takes, so a longer off time is required. On the other hand, if the off time is too long, extra processing time is required. Therefore, when an on time is given, a suitable off time is given. Therefore, next, as shown in FIG. 5, the on-time obtained by approximating the representative data in the actual machining in which the machining result expected based on this theory is stably obtained by an approximate expression. The off time is determined based on basic data indicating a theoretical correlation between the time and the off time (S5).

  By the way, the basic data of the off-time with respect to the on-time is sample data of the off-time with respect to an appropriate relatively small number of on-time, which is known to obtain a stable machining result by test machining. Includes data of an optimum approximation formula set in advance. An approximation formula suitable for the theory that the off time becomes longer as the on time becomes longer is a power approximation. For this reason, the basic data used is expressed as continuous parameter value data with the correlation between the on time and the off time, so even if the on time without sample data is given, it is not just an intermediate value but a theoretical value. The off time when no sample data exists can be obtained as a value. Therefore, it turns out that the off time calculated | required from basic data is a safe value with high reliability.

  Next to the off time, a servo reference voltage is determined (S6). When the servo control is performed so as to maintain the distance of the machining gap by positioning the tool electrode with the average machining voltage, the servo reference voltage is the average machining voltage. The average machining voltage is the product of the discharge standby time and the no-load voltage plus the product of the on time (discharge time) and the machining voltage. Divided by

  Here, the on time and the off time are already determined, but the discharge waiting time is an unspecified time. The no-load voltage is given together with the peak current value data given first. The machining voltage, which is the discharge voltage when a normal discharge that contributes to machining occurs and the discharge current flows, is roughly determined for each material of the tool electrode and workpiece, and the material of the tool electrode and workpiece It can be obtained from basic data indicating the machining voltage for each. Therefore, if the discharge standby time is known, the servo reference voltage can be obtained.

  As described above, the discharge standby time is unspecified and varies in single discharge. However, if there is an actual measurement value, the average non-discharge time in a specific period with respect to the on-time can be obtained relatively accurately. Therefore, the expected machining results based on this theory are stably obtained. Theoretical correlation between on-time and non-discharge time obtained by approximating representative data in actual machining with approximate equations. The non-discharge time is obtained based on the basic data indicating the above, and the discharge standby time is obtained by subtracting the off time from the non-discharge time.

  In this way, other types of machining conditions are sequentially determined using basic data indicating a theoretical correlation between a plurality of types of parameters, and combinations of machining conditions are generated (S7). Therefore, the processing conditions determined in order are determined as a safe value with high reliability with respect to a given parameter value, as long as representative data having a definite parameter value exists at a minimum. Also, several types of processing conditions do not need to be determined one by one exactly one by one, and can be determined simultaneously.

  The above process is repeated for all peak current values that can be taken by the first cut stored in the second storage device 3 first, and a combination of processing conditions is generated for each peak current value (S8). ). The generated combinations of the plurality of processing conditions are stored in the second storage device 3.

  FIG. 7 shows a process for calculating offset values and setting processing conditions in the first cut. FIG. 8 shows a process for inferring the discharge gap. Hereinafter, a method for calculating an offset value in a combination of a plurality of machining conditions generated in the previous process and setting a machining condition in the first cut will be described.

  First, the machined surface roughness is inferred (S11). When the circuit elements in the electric discharge machining circuit are the same, the larger the discharge energy for each discharge, the larger and deeper the discharge trace size. In general, the larger the discharge energy, the rougher the machining surface roughness. Discharge energy is generally determined by the peak current value and on-time. Therefore, the machined surface roughness is the on-time for each peak current value obtained by approximating the representative data in actual machining with an approximate expression, where the expected machining results are obtained based on this theory. And basic data indicating the correlation between the surface roughness and the machined surface roughness.

  However, in the actual electric discharge machining, the machining surface roughness varies due to the influence of the machining environment. Therefore, typical data of the processed surface roughness with respect to the on-time for each peak current value in the basic data used is standard sample data of the processed surface roughness actually measured by the test processing. Further, separate basic data is prepared for the machining depth direction (bottom surface direction) and the side surface direction, and each is approximated by a predetermined approximate expression to improve the reliability of the basic data.

  Next, a side discharge gap is inferred by a calculation process as shown in FIG. 8 (S12). The size of the discharge gap basically depends on the discharge energy. In other words, the parameter that most affects the size of the discharge gap is the discharge energy, and the size of the discharge gap can be roughly estimated from the discharge energy. Discharge energy is generally determined by the peak current value and on-time. Therefore, the side discharge gap is defined as the on-time for each peak current value obtained by approximating the representative data in actual machining, where the machining result expected based on this theory is stably obtained, by an approximate expression. It can be determined based on basic data indicating the correlation with the side discharge gap (S21).

  In actual electric discharge machining, the electric discharge gap varies depending on several factors. The discharge gap estimated based on the discharge energy within the allowable error range in actual machining is sufficient, but depending on the type of parameters that affect the discharge gap, the discharge gap obtained based on the discharge energy is several μm to several A difference of 10 μm may occur. Therefore, when obtaining a combination of machining conditions with more excellent machining efficiency, the basic discharge gap is corrected with factors that affect the discharge gap as much as possible with the discharge gap obtained based on the discharge energy as the basic discharge gap. It is preferable to infer the final discharge gap.

  In the method for inferring a discharge gap in the embodiment, a process for correcting a basic discharge gap obtained based on discharge energy in consideration of several factors is shown. Specifically, the basic discharge gap is corrected based on the no-load voltage, the discharge standby time, and the processing depth. It has been found that when the basic discharge gap is corrected by the no-load voltage, the discharge standby time, and the processing depth, the error between the discharge gap and the basic discharge gap in actual processing can be reduced by several tens of μm. . Accordingly, it is possible to increase the accuracy of the estimated side surface offset value finally obtained.

  When correcting the basic discharge gap obtained based on the discharge energy, first, the basic discharge gap is corrected based on basic data indicating the theoretical relative relationship between the no-load voltage and the corrected discharge gap (S22). ). Next, the discharge gap corrected with the no-load voltage is corrected based on the basic data indicating the theoretical relative relationship between the discharge waiting time for each discharge gap corrected with the no-load voltage and the corrected discharge gap ( S23). In the case of the first cut (S24), since the discharge gap is greatly affected by the machining depth, the theoretical relative relationship between the machining depth for each discharge gap corrected by the discharge standby time and the corrected discharge gap. The discharge gap is further corrected based on the basic data indicating (S25).

  When correcting the basic discharge gap obtained on the basis of the discharge energy in consideration of the parameters affecting the discharge gap, it is not necessary to correct in the order of the above processes. However, when the order of the processes is changed, it is necessary to prepare basic data different from the basic data used for the calculation in the process.

  Finally, a side safety fee is inferred (S13). The safety allowance is to prevent excessive machining, but depends on the variation of the machined surface roughness. Since the variation in the machined surface roughness increases as the discharge energy increases and the machined surface roughness increases, the safety allowance can be obtained by actually measuring the maximum machined surface roughness. Therefore, an accurate safety factor with no possibility of failure can be determined from the target machined surface roughness in actual machining and the measured safety cost sample data. Shows the theoretical relative relationship between the machined surface roughness and the safety factor obtained by approximating the representative data in actual machining with approximate formulas, where the expected machining results are stably obtained based on this theory The safety factor is determined based on the basic data, and the safety margin is inferred by multiplying the machined surface roughness by the safety factor.

  When the machining surface roughness, the side discharge gap, and the side safety allowance are obtained, as shown in FIG. 11, the distance obtained by combining the machining surface roughness, the side discharge gap, and the side safety allowance is set to the side offset value to obtain the final finished surface roughness. Therefore, a distance obtained by adding the desired machined surface roughness is input from the input device 1 as a machining request from a value obtained by adding the machined surface roughness, the side surface discharge gap, and the side surface safety allowance, and is stored in the first storage device 2. The side surface offset value is calculated by subtracting the desired machined surface roughness which is the final finished surface roughness (S14).

  After calculating the side surface offset value, the bottom surface offset value is calculated in the same manner as the side surface offset value (S15). The major difference from the calculation of the side offset value is that the surface roughness, bottom discharge gap, and bottom surface safety allowance are obtained using basic data with the same parameter types but different parameter values. .

  In the calculation of the bottom surface offset value in the embodiment, the bottom surface offset value is calculated for all combinations of processing conditions generated as candidates before determining the combination of processing conditions in the first cut for safety. However, the bottom surface offset value can be adjusted by the feed amount within a predetermined range, so after selecting and setting the combination of machining conditions in the first cut, the bottom surface offset value is only for the set combination of machining conditions. Can be calculated.

  If the side surface offset value is calculated for all combinations of machining conditions generated as candidates (S16), an inappropriate machining speed is obtained with respect to the machining area input from the input device 1 as a machining request. A combination of machining conditions that is a combination of a peak current value, an on-time, and an off-time that becomes an average machining current value is excluded from candidates (S17). At this time, before calculating the side surface offset value, a combination of machining conditions that results in an average machining current value inappropriate for the machining area may be excluded from the candidates.

  For all combinations of machining conditions remaining after eliminating inappropriate combinations of machining conditions, the electrode reduction amount and the order inputted from the input device 1 using the side surface offset value in each combination of machining conditions as a machining request (S18). When the side surface offset value exceeds the electrode reduction amount, the final finished dimension is exceeded and a desired machining shape cannot be obtained, and the combination of machining conditions is excluded from the candidates.

  As the side surface offset value is less than or equal to the electrode reduction amount and is closer to the electrode reduction amount within a predetermined error range, the remaining margin in the first cut becomes smaller. In the machining process after the second cut, the discharge energy is gradually reduced, so the machining efficiency is better as the machining allowance in the machining process after the second cut is smaller. Accordingly, among the remaining combinations of machining conditions, a combination of machining conditions having a side offset value equal to or smaller than the electrode reduction amount and closest to the electrode reduction amount is set as the first cut machining condition (S19). ).

  FIG. 9 shows a process for determining processing conditions in the finishing process. Hereinafter, the process of setting the processing conditions in the processing steps after the second cut will be described.

  Since the machining conditions after the second cut are restricted by the desired machined surface roughness which is the final finished surface roughness, first, the machined surface roughness in each machining process is obtained (S31). The machining surface roughness of each machining process is determined based on basic data indicating the correlation of the machining surface roughness in the next machining process with respect to the machining surface roughness in the preceding machining process. Since the machined surface roughness is gradually reduced, the correlation between the machined surface roughness in a previous machining process and the machined surface roughness in the next machining process is obtained in advance with the desired machined surface roughness. It is represented by a straight line or a curve connecting the machined surface roughness in the combination of the first cut machining conditions.

  When the machining surface roughness of each machining process is determined, a combination of machining conditions is generated for each machining process. As in the case of the first cut, it is possible to set a combination of machining conditions with a candidate combination of a plurality of machining conditions suitable for the peak current value that can be set for the machined surface roughness. The range of peak current values that can be taken is wider than in the case, the number of combinations of processing conditions to be generated increases, and it may take a considerable time to determine the combination of processing conditions. Therefore, in the method of setting the combination of the machining conditions of the machining process after the second cut in the embodiment, the peak current value suitable for the required electrode consumption ratio or machining speed is specified as one, and the peak current value is set. Each kind of suitable processing conditions is determined sequentially.

  When determining the peak current value suitable for the required electrode wear ratio, specifically, first, the basic data indicating the theoretical correlation between the peak current value for each surface roughness and the on-time, the maximum machining Basic data showing the theoretical correlation between the peak current value at which the speed is obtained and the time, and the basic relation showing the theoretical correlation between the peak current value at which the minimum electrode consumption ratio (electrode no consumption) is obtained and the on-time A range of peak current values that can be taken based on the data is temporarily determined (S32). Then, the range of the electrode wear ratio with respect to the range of the peak current value is determined based on the basic data indicating the theoretical correlation between the peak current value for each processed surface roughness and the electrode wear ratio (S33).

  If the electrode wear ratio is not given as a machining requirement, the wear ratio corresponding to the machined surface roughness in the machining process is based on the basic data indicating the theoretical correlation between the machined surface roughness and the wear ratio-oriented ratio. Determine the importance ratio. Basically, the machining area with a larger peak current value consumes more tool electrodes and has a large machining allowance and a machining error, but the machining area with a larger peak current value has a larger machining surface roughness.

  Based on this theory, the theoretical correlation between the machined surface roughness and the wear ratio in each machining step tends to be very similar to the correlation between the peak current value and the wear ratio ratio in the first cut shown in FIG. Can represent relationships. Therefore, based on the basic data showing the theoretical correlation between the peak current value after the second cut and the ratio of importance on the wear ratio created separately from the first cut, an appropriate wear ratio with respect to the machined surface roughness in the machining process. An importance ratio can be obtained. At this time, if the consumption ratio importance ratio is given numerically as the processing request or if the consumption importance degree is given ambiguously as the processing request, the consumption ratio is the same as in the first cut already described. Determine the importance ratio.

  When the wear ratio weight ratio is obtained, the upper limit of the electrode wear ratio is 0%, and the lower limit of the electrode wear ratio is 100%. The electrode consumption ratio is obtained by the ratio (S34). Once the electrode wear ratio is obtained, the peak current value is determined by determining the peak current value relative to the electrode wear ratio based on the basic data indicating the theoretical correlation between the peak current value for each surface roughness and the electrode wear ratio. (S35).

  When the peak current value is determined, the on-time is determined based on basic data indicating a theoretical correlation between the peak current value for each surface roughness and the on-time (S36). When the peak current value and the on-time are determined, the discharge energy is determined.

  In the process of determining the peak current value and on-time, when determining the peak current value based on the required machining speed, the basis for theoretical correlation between the machining speed and the machining speed priority ratio for the peak current value The peak current value can be determined by using the data. Further, the peak current value can be determined by determining the ON time first.

  The machining gap can be stabilized by applying a high voltage when the machining gap is narrow and applying a low voltage when the machining gap is wide. Since the magnitude of the discharge gap basically depends on the discharge energy, the no-load voltage can be determined by the magnitude of the peak current value. Shows the theoretical correlation between discharge energy and no-load voltage obtained by approximating representative data in actual machining with an approximate expression, where the expected machining results are stably obtained based on this theory A no-load voltage is determined based on the basic data (S37).

  The no-load voltage in a general electric discharge machining circuit is determined based on the voltage value that can be set by the power supply voltage, variable power supply voltage, or AC power supply voltage of a combination of multiple DC power supplies. The data is not data represented by continuous parameter values obtained by collecting a plurality of representative data and approximated by a predetermined approximate expression, but corresponds to a specific discharge energy range in a one-to-one correspondence with no-load voltage. The data is shown in tabular form.

  The off time is determined based on basic data indicating a theoretical correlation between the on time and the off time (S38). The servo reference voltage is determined by the discharge standby time obtained based on the basic data indicating the theoretical correlation between the on time and the non-discharge time, and the machining voltage (discharge) roughly determined by the tool electrode and workpiece material. (Voltage) is calculated from the already determined no-load voltage, on-time, and off-time (S39).

  In this way, the processing conditions are determined in a predetermined order for each processing step, and a combination of processing conditions is generated (S40). A combination of processing conditions for each processing step is generated in the same process in each processing step (S41). The generated combination of processing conditions is assigned a processing condition number and stored in the second storage device 3 in the order of each processing step. If a combination of machining conditions is generated in all machining steps, the combination of machining conditions stored in the second storage device 3 may be registered in an existing database stored in the first storage device 2. it can.

  In the case of a finishing process close to the final finishing process or a final finishing process, there are limited combinations of peak current values and on-times that can be obtained in order to obtain the desired surface roughness that is ultimately required. . Therefore, in the final finishing process or a finishing process close to the final finishing process, a combination of processing conditions corresponding to the required processing surface roughness is recorded from a database that records a combination of a number of processing conditions as in the past. It is possible to select and set, and it is not required to set a combination of processing conditions in the processes disclosed in the embodiments in all processing steps.

  Further, in the final finishing process or a finishing process close to the final finishing process, an error between the offset value calculated in the combination of the set processing conditions and the offset value in actual processing is small. In any case, too much machining is not allowed, so any machining will always be finished within the desired machining geometry within the expected machining error range. Even if a combination of machining conditions corresponding to the required surface roughness is extracted from the database of combinations of existing machining conditions within the range of Dynamic amount can be obtained.

  When a combination of machining conditions in each machining process is generated, a side surface offset value and a bottom surface offset value in the machining condition combination are obtained for each machining process. Basically, the side surface offset value and the bottom surface offset value can be calculated in the same process as in the case of the first cut.

  However, in the first cut, there is a large variation in the discharge gap in the range of several tens of μm depending on the machining depth, but in each machining process after the second cut, machining is performed with the tool electrode inserted in the machining hole. Therefore, the size of the discharge gap hardly changes with respect to the processing depth. Therefore, as shown in FIG. 8, when the discharge gap is inferred, if it is after the second cut (S24), it is not necessary to correct the basic discharge gap based on the discharge energy according to the processing depth.

  The basic data used in each processing step after the second cut is data having the same parameter type and different parameter values as the basic data in the first cut. In the final finishing process, the side surface offset value and the bottom surface offset value correspond to the side surface discharge gap.

  A process for setting the feed amount in the machining depth direction in each machining process including the first cut and the swing amount in each machining process after the second cut will be described below. The feed amount in the first cut is obtained from the processing depth and the bottom surface offset value in the first cut. The feed amount of the first cut is obtained by a distance obtained by subtracting the side surface offset value from the machining depth input from the input device 1 as a machining request. In actual machining, as shown in FIG. 10, since machining is started from the machining start position, the distance at which the tool electrode is sent by the first cut is a distance obtained by adding the distance from the machining start position to the upper surface reference. . However, when creating the NC program by the absolute method, it is understood that it is sufficient to give the feed amount from the upper surface reference because the command is given at the coordinate position.

  The feed amount of each machining step after the second cut is obtained from the bottom surface offset value in the preceding machining step and the bottom surface offset value in the next machining step. As shown in FIG. 10, the feed amount in the next machining step is a value obtained by subtracting the bottom surface offset value in the next machining step from the bottom surface offset value in the previous machining step.

  The swing amount of each processing step after the second cut is obtained from the side surface offset value or electrode reduction amount in the first cut and the side surface offset value in each processing step. As shown in FIG. 11, the rocking amount in the next machining step is a value obtained by subtracting the offset value in the next machining step from the first cut side surface offset value or the electrode reduction amount.

  The feed amount is converted into a movement command value, and a movement program is generated. The swing amount is stored corresponding to a combination of processing conditions. The machining time is calculated from the combination of machining conditions, and each machining condition generated is processed as a machining plan in the form of a machining condition table along with machining result data such as machining surface roughness, machining time, offset value, and oscillation amount. It is displayed on the display screen of the display device.

  The generated movement program data is converted into the NC program format as the main part of the NC program. Further, the data of the combination of each machining condition expressed in the form of the generated machining condition table is converted into the NC program format as the header part of the NC program. The main part and the header part are combined and output as a data file of one NC program, and a data file name is given and stored in the first storage device 2.

  The machining condition setting device described above is not limited to the configuration of the embodiment as already described some modifications, and is changed, replaced, or added without departing from the technical idea of the present invention. It is possible to carry out with modification as follows. Further, it can be used in combination with an existing machining condition setting device having a machining condition database in which combinations of a plurality of machining conditions are recorded.

  The machining condition setting device of the present invention is applied to a die-sinking electric discharge machining device for machining a mold or a part. According to the present invention, a combination of safe machining conditions with high machining efficiency and high reliability can be set more easily. As a result, the machining efficiency of metal machining by electric discharge machining is improved, contributing to the development of electric discharge machining.

It is a block diagram which shows the structure of the processing condition setting apparatus of this invention. Basic data showing the theoretical correlation between the peak current value and the on-time for obtaining the maximum machining speed, and the theoretical correlation between the peak current value and the on-time for obtaining the minimum electrode wear ratio (no electrode wear). It is a graph to represent. It is a graph showing the basic data which shows the theoretical correlation with the ON time for every peak electric current value, and an electrode consumption ratio. It is a graph showing the basic data which shows the theoretical correlation of a peak current value and a consumption ratio weight ratio. It is a graph showing the basic data which shows the theoretical correlation of on time and off time. It is a flowchart which shows the process which produces | generates the combination of process conditions from the peak current value which can be taken by a first cut. It is a flowchart which shows the process of setting the processing conditions in calculation of an offset value and a first cut. It is a flowchart which shows the process of inferring a discharge gap. It is a flowchart which shows the process which determines the process conditions in a finishing process. It is a side view which shows typically the processing aspect of a process depth direction. It is a side view which shows typically the processing aspect of a side surface direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input device 2 1st memory | storage device 3 2nd memory | storage device 4 Arithmetic device 41 Machining condition production | generation part 42 Machining surface roughness inference part 43 Discharge gap inference part 44 Offset value calculation part 45 Machining condition setting part

Claims (13)

An input device for inputting a machining request which is information related to machining indicating a restriction in machining, and a storage device storing a plurality of types of basic data indicating a theoretical correlation between a plurality of types of parameters including the machining conditions and the machining request selects a plurality of peak current value which can be taken by the first cut, sequentially determined based on each type of processing conditions suitable for the respective peak current value to the basic data to generate a combination of a plurality of sets of processing conditions, wherein For each combination of machining conditions, obtain the basic side discharge gap from the correlation between the on-time for each peak current value and the side discharge gap, and at least the no-load voltage and correction for each side discharge gap before correction Correlation with side discharge gap after correction, correlation between discharge standby time for each side discharge gap before correction and side discharge gap after correction, before correction After obtaining the side surface discharge gap by correcting the basic side surface discharge gap from any one or more of the correlations between the processing depth for each surface discharge gap and the corrected side surface discharge gap, a desired processing surface is obtained. Side surface in the combination of the machining conditions generated from the roughness and the machining surface roughness in the combination of the machining conditions obtained based on the basic data, the corrected side surface discharge gap, and the side surface safety allowance. An arithmetic unit that obtains an offset value based on the basic data and sets a combination of processing conditions to obtain a side offset value suitable for the electrode reduction amount input as the processing request as a combination of first cut processing conditions; A machining condition setting device for EDM with EDM. 2. The machining condition setting device according to claim 1, wherein the arithmetic device selects a combination of machining conditions for obtaining an average machining current that can be taken with respect to a machining area from the plurality of combinations of machining conditions. . The arithmetic unit sets a combination of processing conditions for obtaining a side surface offset value that is a value equal to or smaller than the electrode reduction amount and closest to the electrode reduction amount as a combination of first cut processing conditions. The processing condition setting device according to claim 1. The processing condition setting device according to claim 1, wherein the arithmetic device obtains a bottom surface offset value in the combination of the processing conditions based on the basic data. The processing condition setting device according to claim 1 , wherein the arithmetic unit obtains a feed amount in a processing depth direction in the first cut from a processing depth and a bottom surface offset value in the first cut. The arithmetic unit obtains a bottom surface offset value in the combination of the machining conditions from a machining surface roughness, a bottom surface discharge gap, and a bottom surface safety allowance in the combination of the machining conditions obtained based on the desired machining surface roughness and the basic data. The processing condition setting device according to claim 4 , wherein: The arithmetic unit obtains a basic bottom surface discharge gap from the correlation between the ON time for each peak current value and the bottom surface discharge gap, and at least the no-load voltage for each bottom surface discharge gap before correction and the bottom surface discharge gap after correction. Correlation between the discharge standby time for each bottom discharge gap before correction and the bottom discharge gap after correction, and the correlation between the processing depth for each bottom discharge gap before correction and the bottom discharge gap after correction. The machining condition setting device according to claim 6 , wherein the bottom discharge gap is obtained by correcting the basic bottom discharge gap from any one or more correlations. The computing device obtains the machining surface roughness in each machining process after the second cut based on the basic data from the desired machining surface roughness and the machining surface roughness in the combination of the machining conditions, and for each machining process. The processing condition setting device according to claim 1, wherein a combination of processing conditions for each processing step is set based on a processing surface roughness in each processing step. The arithmetic device determines a peak current value based on the basic data from a machined surface roughness in the machining process in at least one machining process of the machining processes, and sets various types of machining conditions suitable for the peak current value. 9. The machining condition setting device according to claim 8 , wherein a combination of machining conditions is set by sequentially determining based on the basic data. 9. The machining condition setting apparatus according to claim 8 , wherein the arithmetic unit obtains a bottom surface offset value and a side surface offset value in each combination of the machining conditions based on the basic data. The arithmetic device comprises a machining surface roughness, a bottom discharge gap, and a bottom surface safety allowance in a combination of the desired machining surface roughness and the machining conditions of each machining process obtained based on the basic data for each machining process. The processing surface roughness and side surface in the combination of the processing conditions of each processing step obtained based on the desired processing surface roughness and the basic data for each processing step, respectively, for determining the bottom surface offset value of each processing step The processing condition setting device according to claim 10 , wherein a side surface offset value of each processing step is obtained from a discharge gap and a side surface safety allowance. The arithmetic unit obtains a basic bottom surface discharge gap from the correlation between the ON time for each peak current value and the bottom surface discharge gap, and at least the correlation between the no-load voltage and the bottom surface discharge gap to be corrected and the discharge standby time. And correcting the basic bottom surface discharge gap from any one or more of the correlations between the bottom surface discharge gap and the bottom surface discharge gap to be corrected to obtain the bottom surface discharge gap of each processing step, and for each peak current value The basic side discharge gap is obtained from the correlation between the on-time and the side discharge gap, and at least the correlation between the no-load voltage and the corrected side discharge gap and the correlation between the discharge standby time and the corrected side discharge gap. The basic side surface discharge gap is corrected from any one or more correlations with the relationship to determine the side surface discharge gap of each machining step. Processing condition setting apparatus according to claim 11, wherein Rukoto. The arithmetic device obtains the feed amount in the machining depth direction in each machining step from the bottom surface offset value in the previous machining step and the bottom surface offset value in each machining step, and the side offset value in the first cut and the The machining condition setting device according to claim 10 , wherein a swing amount in each machining process is obtained from a side surface offset value in each machining process.

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